The invention relates generally to the real time detection and identification of chemical or biological macromolecules via non-destructive testing, and more specifically to a programmable active microwave (GHz to THz in the most preferred embodiment) ultrafine resonance spectrometry system, apparatus and method.
There exists a great need for a remote sensing system capable of macromolecule substance detection and identification. As used herein, the term macromolecule means a large molecule like a polymer, for example, made up of many (a few to millions) of repeating subunits. A definition for a macromolecule from physical chemistry includes a molecule that has molecular motion of two types: intramolecular modes (xe2x80x9coptical photonsxe2x80x9d) and lattice vibration (xe2x80x9cacoustic phononsxe2x80x9d). The intramolecular modes are low frequency torsions, ring puckering and hindered rotations generally present in the gas phase but modified by the solid state environment. The term macromolecules includes both complex inorganic (e.g., nitrogen-based explosives) and long-chained DNA polymers. The prior art includes spectrometer systems, high-energy cross-section absorption systems, and polymerase chain reaction systems that are used for the detection and identification of macromolecules.
Prior art spectrometer systems are based on quantum mechanics, and application of statistical sampling theory to identify macromolecules. These systems query a large sample space, are likely to contain undesired materials which act as interferents and contaminants, collectively used herein as foreign bodies. An interferent typically exists separate from the macromolecule and may interfere with spectroscopic measurement through absorption and attenuation of incident measuring radiation. A contaminant may be attached or otherwise reactively associated with a macromolecule and may interfere with spectroscopic measurement through its absorption and attenuation of incident measuring radiation or through altering the response characteristics of the associated macromolecule.
Many prior art systems take large numbers of samples to amplify any signal. Mass spectrometers may require days of sample acquisitions to achieve the required integration.
High-energy cross-section absorption systems are also based upon quantum mechanics and require long integration times. Moreover, they use a single spectrum query. Several macromolecule species may contain the same unique spectral absorption (e.g., packed wool and explosives).
Polymerase chain reaction systems rely on statistical sampling of antigen interactions, and consequently may take minutes to hours before threshold detection levels are achieved. Furthermore, these systems require special handling, may easily be contaminated, and are expensive to build and maintain.
As an example of a specific prior art system, none of the existing methods for the remote detection of hidden illicit drugs and drug-containing plants is completely adequate. Techniques based on the detection of vapors, both of drugs and the precursor processing chemicals are not sensitive to drugs, because drugs generally have a negligible vapor pressure at room temperature. X-ray techniques are not very selective for drugs, as they penetrate without absorption or reflection.
The preferred embodiment of the present invention provides a programmable active microwave (GHz to THz) ultrafine resonance spectrometer (PAMURS) instrument. The systems described herein may be used to cover frequencies from the far infrared to the deep ultraviolet, about 1xc3x971012 Hz to about 3xc3x971016 Hz, the range from microwaves to X-rays. This PAMURS instrument overcomes the limitations of the prior art macromolecule detection, identification and disruption/elimination systems.
Some key advantages derive from the characterization of such a PAMURS instrument as a real-time system. The PAMURS instrument, in a preferred embodiment, combines several operational modes, such as initialization in a broadband search mode (e.g. any DNA detected), which may be subsequently switched to a narrowband mode for specific identification of one or more types of macromolecules. When a macromolecule is detected, the PAMURS instrument is able to rapidly progress through a library search to narrow down and specifically identify the detected material. The preferred embodiment of the PAMURS instrument is highly accurate due to use of multiple frequencies to create a xe2x80x98notch filterxe2x80x99 for recognizing a macromolecule resonating at only the selected group of frequencies. As the number and precision of the applied frequencies increases, it becomes less likely for two different macromolecules to be identified as the same macromolecule.
The PAMURS instrument uses absorption spectra and emission spectra for detection and identification. Two distinct macromolecules having the same absorption spectra are unlikely to have identical emission spectra, as the decay function is related to the macromolecule""electric field and its mass. This is particularly true as catalogs of xe2x80x98signaturexe2x80x99 spectra for the various macromolecules of interest are developed. These catalogs make the PAMURS instrument adaptable, as new frequency sets may be uploaded to the instrument library as required or desired.
The PAMURS instrument is able to screen out interferents and contaminants (particularly water vapor and ozone absorption) due to use of the narrow band spectra chosen and the use of a multiple beam approach. The PAMURS instrument is able to detect and identify very low thresholds of macromolecules (on the order of parts per billion) because it is a radio frequency (RF) based instrument. RF based systems have inherent high signal-to-noise, with consequent low error rates. Further, the likelihood of false positive detection is low. For these reasons, a PAMURS instrument may be a remote sensing imaging system because the ozone and water vapor absorption bands in the THz ranges may be avoided by the narrow RF bandwidths. In another preferred embodiment, a PAMURS instrument may be an inhaler/sampler for airborne and waterborne applications.
The PAMURS instrument has a direct relationship between the power employed by the system, and the rate and distance of the detection. By increasing the power of the PAMURS instrument, the detection rate increases for both aerosols and surface materials, and the detectable distance of the macromolecules from the sensor increases as well.
The narrow signals used by the PAMURS instrument decreases the risk of interference with other RF signals. The exposure risk to humans from irradiation is minimal due to the frequencies and the low power levels used.
Theoretical predictions for a PAMURS instrument indicate that it should have minimal Type II Errors as resonance signal returns are similar to those that would be that transmitted (i.e., there should be no unexpected signal returns) unless an unexpected Doppler shift occurs.
A preferred embodiment of the present invention includes a system for detecting a presence of a macromolecule having one or more resonant frequencies. The system includes a pulse generator (a T-wave generator in the most preferred embodiment) for generating a detection profile having a detection set of T-waves and applying the detection profile to a sample including the macromolecule, at least one T-wave having a center frequency substantially centered on one of the resonant frequencies of the macromolecule, a detector for receiving the detection profile after the application of said detection profile to said sample, an analyzer, coupled to the detector, for determining a T-wave absorption profile by identifying which T-waves of the set of T-waves have been wholly or partially absorbed by the sample and to subsequently identify the macromolecule by use of the absorption profile.
Another preferred embodiment of the present invention includes a system for detecting a presence of a macromolecule having one or more resonant frequencies. The system includes a T-wave generator for generating a detection profile having a detection set of T-waves and applying the detection profile to a sample including the macromolecule, at least one T-wave having a center frequency substantially centered on one of the resonant frequencies of the macromolecule, the resonant frequency inducing the macromolecule to reradiate an emission profile including a set of emission frequencies different from frequencies of the set of T-waves, a detector for receiving the emission profile after the application of the detection profile to the sample; and an analyzer, coupled to the detector, for determining a T-wave absorption profile by identifying which T-waves of the set of T-waves have been wholly or partially absorbed by the sample as derived from the emission profile and to subsequently identify the macromolecule.
Reference to the remaining portions of the specification, including the drawing and claims, will realize other features and advantages of the present invention. Further features and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention, are described in detail below with respect to accompanying drawing. In the drawing, like reference numbers indicate identical or functionally similar elements.